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Questions and answers

General questions

How are you able to tell the age of a Vetter product?
You are able to tell the age of Vetter products by the serial number.
From August 1994 onwards an eight digit number is used (e.g. 01115678).
The first two digits indicate the month of production (in this case January).
The next two digits indicate the year of production (in this case 2011).
The following four digits are only product-related numbers and have no connection with product age.  
 
How is the air requirement calculated?
The maximum air requirement is the volume of air in litres that is necessary to produce the maximum permitted operating pressure in the unloaded condition at normal room temperature. The maximum air requirement can be calculated by the following formula:

Nominal capacity in litres * (permissible operating pressure in bar + 1 bar surrounding atmospheric pressure)

Example:

A S.Tec 12 Lifting bag has a nominal capacity of 61,4 litres and a permissible operating pressure of 12 bar/174 psi. The atmospheric pressure is normally 1 bar/14.5 psi.
This results in an air requirement of 798,3 litres.  
 
Why are there different coupling systems?
In order to ensure that no controller having a higher operating pressure is connected to a product with a lower operating pressure, the manufacturer of controllers, products and inflation hoses has fitted them with coupling systems which correspond to the pressure category.

For example, if the user were to inflate a lifting bag (1 bar/14.5 psi) with a controller for a S.Tec 12 Lifting bag (12 bar/ 174 psi) then the bag would unavoidably burst due to the extremely high inflation pressure.
The regulations for product liability oblige the manufacturer to design a product which eliminates human error to the greatest extent possible.
However, due to the different coupling systems this error is eliminated.  
 
Why do the inflation hoses have different colours?
The colour of the inflation hose simplifies correct control of the different bags when in operation. Precisely when the position of individual bags have to be changed due to the operation situation it may happen that wrong bag control takes place because the side arrangement of the bags in relation to the controller is no longer the same. The bag arrangement to the controller is simplified by hose colours.  
 
Why must a controller be used?
Pressure devices must be protected against unintentional over-inflation. The component-tested safety valve on the controller stops a product being pressurized at a pressure higher than the permitted operating pressure.
If, due to additional load, there is a pressure increase in the product then the safety valve will activate and counter this increase.
The specified manometer reliably indicates the bag pressure. In addition to this there is a blocking and releasing device for safe bag operation.  
 
What does the safety factor signify?
The safety factor gives the relationship between the bursting pressure and the permissible operating over-pressure. For example, if a S.Tec 12 Lifting bag 12 bar/174 psi has the safety factor "4" then the bursting pressure must be 48 bar/694 psi.  
 
Who is allowed to re-seal a safety valve?
Safety valves are given a seal as a visual indication against non-permitted adjustment.
At present there is a difference between customs seals and seal plates.

If the corresponding seal is no longer available then the safety valve (on the controller or the inflation hose and safety hose) is not allowed to be used any more. If the specialist has the corresponding measurement device as well as his own sealing pliers then he is allowed to re-seal the safety valve. Otherwise the safety valve must be exchanged for a new one.  
 
Are you allowed to repair piston valves?
Generally, defective piston valves are only allowed to be maintained by a specialist.
However, in order to exchange the sealing ring of the piston rod considerable time is required for the repair in addition to having the corresponding special tool.
If material and time is calculated, it is generally better to exchange the complete piston valve.  
 
Who is allowed to re-bond defective hoses?
If required, inflation hoses and air supply hoses can be fitted with new coupling components by a specialist.
In doing this it is not necessary to use crimp sleeves because this requires a special tool; normal hosing sleeves can be used.
Generally a repaired sleeve should be tested for leaks at 1.5 times the operating pressure.  
 

Pipe and Test sealing Bags

When do pipe and test sealing pads need to be discarded?
There is no stipulated time specification for discarding the pipe and test sealing pads.
Decisive for possibly-necessary discarding is the results of regularly scheduled, mandatory tests performed on the pipe and test sealing pads as per BGR 126, BGR 117, BGI 802, BetrSichV (German Operational Safety Code) and ArbSchG (German Industrial Safety Act ) and the manufacturer's testing regulations. For more information please refer to the operating instructions in the download section.
 
 
How do the pads need to be stored?
The sealing pads should always be stored, just like other rubber products, in accordance with DIN 7716 in a cool and dry place.
 
 
Can the pads be repaired?
Only corrective maintenance to a slight degree in case of small damage points in the area of the expandable pad surfaces is possible. A set of repair materials is available on request.
The operating organisation can also easily replace connection couplings, etc.
 
 
What is the pad resistant to?
Pipe sealing pads and test sealing pads, just as with leakage sealing pads, are resistant to a number of acids, alkalines and solvents (see the chemical resistance list in the catalogue).
You can request a detailed chemical resistance list from the manufacturer. We are glad to provide material samples for your own investigations of the chemical resistance.

 
 
Do the pads have to be braced?
Due to the water backpressure, pipe-sealing devices often have to withstand large pressure forces. For that reason the pad, especially when using large pipe dimensions, must be braced frictional to the pad. According to the UVV (Accident Prevention Standards), bracing is mandatory during pressure tests.  
 
How can the coupling and the valve extension be replaced?
Connection couplings and valve extensions are fixated on the pad connecting thread with a two-component, synthetic-resin adhesive.
To release them, this bond must be carefully heated with a hair dryer until the coupling can be easily unscrewed.
While doing so, avoid directly heating up the rubber material. After that, screw the replacement coupling on again together with the adhesive and let it cure for at least 24 hours.

 
 
Can I uncouple the pad without it losing air?
Tube sealing pads and test sealing pads are, just as with leakage sealing pads, equipped with an automatically-closing connection coupling. If the filling hose is uncoupled, the valve automatically closes and the pad remains pressurised. The 1.5 and 2.5 bar filling hoses are also equipped with automatically-closing couplings.  
 
What counter pressure do the pads withstand?
The amount of the max. counter pressure in the pipeline depends on many factors, e.g., the pipeline material, etc.
0.5 bar pipe sealing pads and testing pads are tested for a max. counter pressure of 2 m WC;
1.5 bar pipe sealing pads and testing pads are tested for a max. counter pressure of 5 m WC; the pads with working overpressures of 2.5 bar are tested for a counter pressure of 10 m WC. Please refer to the last page of the catalogue for exact information on the counter pressures.
 
 
How long can the pads remain in the channel?
No time limit is specified for the service life of sealing pads. During long deployments however, periodic checks, e.g. daily, of the working overpressure should be performed in the pads.